Automatic electrical control device



Feb. 6, 1940. R. w. BONNER ET AL AUTOMATIC ELECTRICAL CONTROL DEVICE Filed March 15, 1937 INVENTORS RAYMOND w. BONNER PHIL o. HALL MM ATTORNEYS UNITED srA'rss PATENT OFFICE AUTOMATIC ELECTRHGAL CONTROL DEVICE Raymond W. Bonner and Phil D. Hall, Detroit,

Mich, assignors, by direct and mesne assignments, of one-half to Raymond W. Bonner and one-half to Harry M. Kirschbaum, Detroit,

Mich.

Application March 15, 1937, Serial No. 131,086

3 Claims. (01. 250--36) The invention relates to electrical control devices of that type sensitive to the presence of a person or object in its vicinity. Certain constructions belonging to this type are operated by 5 the interruption of a beam of light which is norperson within a given range of a predetermined 5 mally focused on a light sensitive electric cell. point to start an electrical oscillation and to This necessitates the mounting of the source of thereby operate a relay. light and the sensitive cell at spaced points so As specifically shown in Figure 1, our improved positioned that the controlling persons or objects apparatus includes a pentagrid mixer tube A, a

may pass therebetween. There are, however, rectifying tube 13 and a pentode amplifying tube 10 many uses for an automatic control where it C, together with cooperating elements and elecwould be diflicult to make such an installation. trical circuits as follows:

Also, such constructions are costly and are easily I) is the service connection from which a pair r thrown out of order. of conductors l and 2 lead to the heaters 3, 4,

It is the object of the present invention to 010- and 5 respectively of the tubes A, B and C and 15 tain an electrical control, the sensitive element of which are in series with each other and with a which is operable by the presence of a person or resistor E3. The tube A has a cathode 7, a plate 8 object within a predetermined distance thereand the intermediate grids 9, Iii, H, Ha, and 12.

n from or, if desired, only within predetermined The grids H and Ma are screen grids and are limiting angles. It is a further object to obtain a connected to the conductor 2 through the mediconstruction which difierentiates between certain urn of conductors l3 and i l. The grid [2 is a objects and others having different capacities, conventional suppressor grid and is connected to and more particularly one which is sensitive to the cathode T. The grid 9 is connected to the W the proximity of a human being, but is unaffected conductor l through the medium of a potentiomby an inanimate object or an animal of a differeter including the resistor t5 and contact 16 ent species having a capacity differing from that movable with respect to the resistor 6. ii and of a human being. A further important object iii are inductances in series, one terminal being of the invention is to obtain a construction which connected by a conductor ill with the conductor l while utilizing electrical oscillations, will not inand the other through a conductor Kit with a terfere with radio apparatus in its vicinity. Still blocking condenser 2! intermediate the same and further it is an object to obtain a comparatively the grid 9. A tuning condenser 22 is connected inexpensive construction and one which is comin parallel with the inductances H and I8 to the posed of elements of standard construction. conductors l9 and 29. The plate 8 is connected With these and other objects in view, the in'vento the conductor It through a loading resistor 23 tion consists in the construction as hereinafter and conductor 24, and also through a blocking set forth. condenser 25 with the conductor 20. intermediate In the drawing: the heaters 25 and 4. Figure 1 is a diagram illustrating the electri- The rectifying tube B is of the full-wave type cal instruments and circuits constituting our imhaving the cathodes 25 and 2'! and plates 25 and 40 proved control; 29. The plate 25 and cathode 2? are connected 40 Figure 2 is a perspective view of a casing in by a conductor 3b with the cathode l of the tube which the control may be located; A. The cathode Zliis connected through con- Figure 3 is a plan view of the construction ductor toa center tap between the inductances shown in Figure 2 indicating in dotted lines the l! H3. The plate is connected by conextent of the field of responsiveness. ductor with an inductance which might be In the present state of development in the termedaflcating inductance and the other termiradio art certain standard constructions of tubes nal or" which is connected through a conductor 35% and other elements are available for various uses. with. the control grid iii of the tube A. There is These include tubes which in connection with the further a connection 35 including a block ng conproper hook-up will generate electrical oscilladenser St between the conductor an... trip 50 tions of predetermined frequencies; also, tubes for relatively low frequencies or what is generally known as audio-frequency. There are further, tubes which may be used as either half-wave or full-wave rectifiers. Making use of such tubes and other standard parts of radio equipment, we have devised an apparatus which is normally in an inactive condition, but which is affected by a change in capacitance due to the presence of a plate E. The grid M2 in the tube A is connected to the cathode l. The plate 251 of the tube has an output conductor this connected by a dropping resistor 38 with the conductor I.

The output from the tube A is taken from the nary practice, and is impressed upon the full wave rectifier tube B which produces a positive voltage .and a negative voltage.

In detail, the tube elements 25 and 28 produce a positive voltage which is sent through the conductor 3! and the tuned circuit comprising the condenser 22 and the in ductances l1 and I8 to the control grid e of the tube A. The tube elements 21 and 29 of the tube B produce a negative voltage which is applied to the inductance 33 and the control gridill of the tube A through the conductor 32, and to the grid 4! of the tube C through the conductor 3'5. When capacitance is added to the circuit including the inductance 33 by reason of the approach of a body within the field of a trip plate E, the impedance of this circuit is changed, effecting a decrease in negative voltage to the grid M of the tube C or, in other words, causing the grid il to become more positive with respect'to the cathode, thereby enabling current to flow through the tube C to operate the relay 48. At the same time, the increased flow through tube A is progressively increased by reason of the feed back to the control grid, 9 of this'tube through the tuned circuit containing the condenser 27 and the inductances l! and M3. in-- suring a continued operation of the relay as long as the body remains in the field of the trip plate The introduction of capacitance into the circuit containing inductance 33 changes the tuning of this circuit, and inasmuch as the two circuits inductively coupled, the circuits automatically become tuned to each other at a new balance point.

Any suitable means for amplifying the current may be used, but as shown we employ a pentode tube C having a cathode 39, plate 40 and intermediate grids M, 43 and M. The cathode is connected to the conductor l through the conductor 35 The conductor 31 from the rectifying tube B is connected with the grid 4!. The grid 44 is connected to the cathode 39 and the grid is connected through the medium of a conductor 45 and conductor 14 with the conductor 2. A conductor' 46 connects the conductor 2 to the coil 4! of a relay 48, the opposite terminal of said coil being connected by a conductor 49 with the plate Ml. A condenser 59 is also placed parallel to the coil 4'! between the conductors 46 and 49. Thus in operation the output from the plate 29 of the tube 13 is conveyed through the conductor 31: to the grid 4! causing electronic discharge from the cathode 39 to the plate 4!), and thus amplifying the current through the conductor 49, coil t1 and conductor 46. This current is sufiicient in volume to operate the relay.

The trip plate E may be formed of any conductive surface connected to the circuits as described. One construction illustrated in Figures 2 and 3 is a glass plate having a light film of silver deposited thereon. orwhat is known as an invisible mirror. This may be arranged either immediately adjacent to the tubes as indicated in.

Figures 2 and 3 or at a more or less remote point.

By suitably adjusting the condensers 22 and 36 the circuits may be properly balanced with the trip plate so that under normal conditions the tubes are substantially inactive with'insufiicient current passing through the coil of the relay to operate the same. When, however, any person comes within a certaindistance of the trip plate the balance will be destroyed causing the tubes A, B and C to function and operate the relay.

An important feature of our improvement is that not only are the circuits normally balanced so that the tubes are inactive, but also after the destroying of this balance a new balance is effected which maintains the electronic discharge in the tubes and the current through the relay substantially constant as long as the increased capaci tance is maintained. tance affecting the trip plate E destroys one balance, butestablishes another. Anotherfeature is that by adjusting the movable contact it of the potentiometer the field of sensitiveness extending from the trip plate may be enlarged or diminished. Thus if it is desired to have the device respond only to a person quite close to the plate such adjustment can be made. On the other hand, if a greater distance of response is desired this also can be obtained by suitable adjustment. Thus, as shown in Figures 2 and 3, the trip plate E has a silver film on the back of a glass plate E which forms the front of the cabinet F within which the instrument is located. This cabinet is either made of metal or is provided with a metallic screen shielding the side and rear walls thereof so that the field of response is'almost entirely in front of the glass E By adjusting the potentiometer this field may be extended as indicated by the dotted line G, or if desired may be limited as indicated by the dotted line 1-1. It is, of course. unnecessary that the trip plate should be closely associated with the tubes and other elements of the instrument, but where separated therefrom it is desirable to also shield the connecting conductor.

As previously described, it is very important that the control device should not produce interference with the operation of radio instruments in its vicinity. This is accomplished primarily by keeping the frequency of oscillation below a predetermined point and also by limiting the electrical energy employed. An exceedingly small amount of electrical energy and a frequency of less than 50 kilo'cycles will be sufficient for satisfactory operation.

Some or the uses for which'our improved control mechanism is adapted are:

(1) To actuate advertising devices using invisible mirrors;

(2) To light up showcases or display cabinets;

(3) As a burglar alarm;

(4) To turn out porch lights, room lights, etc;

(5) To illuminate sign boards;

(6) To start and stop any motor driven appliance;

(7) To start and stop motor driven window dis (8) To count persons passing a given point;

(9) For safetydevices:

What we claim as our invention is:

1. An electrical discharge control device comprising a valve tube, a gridless second tube having pairs of cathodes and plates in opposed relation, a service connection to the plate of said first tube having a loading resistor therein, a connection between the cathode of said first tube and one of the plates and one of the cathodes of said gridless tube, an oscillation circuit between the other of said cathodes and one of the grids of said first tube, said circuit including a pair of inductances and a capacitance normally tuned to a frequency within the audio range, a second oscillation circuit connected to the other plate of said gridless tube and extending to another grid of said first tube, said second circuit including an inductance in inductive relation to the aforesaid inductances,' a potentiometer connected to the grid of said first circuit for placing a variable In brief, change in capacisaid potentiometer connection and said first circuit, and a trip member connected to said second circuit responsive to a capacitance when moved Within a, predetermined field area thereof.

2. A capacity controlled electrical circuit comprising an electron tube having a pair of control grids, an oscillation circuit connected to one of said control grids, a second oscillation circuit connected to the other of said control grids and inductively coupled to said first oscillation circuit, a full wave rectifier tube connected to the output of said first mentioned tube and having its positive Voltage output impressed upon one of said oscillation circuits and its negative voltage output impressed upon the other oscillation circuit, and a trip member connected to one of said oscillation circuits and adapted to change its capacity upon the approach of a body, thereby effecting a change in the tuning of said oscillation circuits and increasing the output of said electron tube and said rectifier tube.

3. A capacity controlled electrical circuit comprising an electron tube having a pair of control grids, a plate, and a cathode, a full wave rectifier tube having a pair of plates and a pair of cathodes, means connecting the cathode of said electron tube with one of the plates and one of the cathodes of the rectifier tube, a voltage supply connected to the plate of said electron tube, an oscillation circuit having inductance and capacitance connected to the other cathode of said rectifier tube and to one of the control grids of said electron tube, a second oscillation circuit having inductance connected to the other plate of said rectifier tube and to the other of said control grids, said oscillation circuits being inductively coupled, a device to be operated operatively connected to the last mentioned plate of the rectifier tube, and a trip member connected to said second mentioned oscillation circuit and adapted to change its capacity upon the approach of a body, thereby efiecting a change in the tuning of said oscillation circuits and increasing the output of the electron tube and the rectifier tube and operating the device to be operated.

RAYMOND W. BONNER. PHILD. HALL. 

